The present invention relates generally to electronic devices, and more particularly to an electronic integrated circuit card, i.e., smart card, that provides additional electrical connectors or contact pads, so as to provide additional functional capability, speed and/or larger memory capacity for the smart card.
The typical prior art smart card contains an integrating circuit processor, a small amount of memory, and an interface circuit. Typical applications of prior art smart cards include telephone calling cards and stored value cards. More recently, smart cards have been utilized to control access of users to various systems such as banking, internet or other electronic security systems.
Currently, most prior art smart cards are fabricated in accordance with an international standard, namely the International Standard Organization/International Electrotechnical Commission (ISO) 7816 standard. As is well known, in the ISO 7816 standard a card reader is employed to interface between the smart card and a host computer. The card reader communicates with the smart card in accordance with the ISO 7816 standard, and communicates with the host computer via an interface such as a RS-232, a PS/2 or a universal serial bus (USB). One example of a specialized prior art smart card and card reader and its communication protocol with a host computer is disclosed in U.S. Pat. No. 6,168,077 entitled Apparatus and Method of Providing a Dual Mode Card and Reader issued Jan. 2, 2001 assigned to Litronic, Inc., the Assignee of the subject application, the disclosure of which is expressly incorporated herein by reference.
The ISO 7816 standard specifies the dimensions, locations and assignment for each of the electrical contacts or contact zones formed on the smart card which then interface with conventional smart card readers. The plural contact zones or pads are designated by the ISO 7816 standard as zones or pads C1 through C8. The pads C1 through C4 are separated by a central region on the card from pads C5 through C8. This void or central region has heretofore been utilized to facilitate the mounting of the integrated circuit die with the integrated circuit die being attached on one side of the carrier while the contact pads C1 through C8 being formed and disposed on the opposite side of the carrier. The integrated circuit die has hereto been electrically connected to the contact pads C1 through C8 via conventional bonding wiring techniques which require that the central area of the carrier existing between the contact pads C1 through C8 be connected to ground via contact pad C5. As a result, the entire central region or portion of the carrier located between the contact pads C1 through C4 and C5 through C8 has not been available for additional contact pads, but rather has been used solely to provide mounting of the integrated circuit die to the smart card.
In view of the above, the number of connector zones to the smart card have been limited to the zones C1 through C8 which, as will be explained in more detail infra, serves to limit the function and memory of prior art smart cards.
As such, there exists a substantial need in the art to provide additional conductive pads on a conventional smart card in conformity with the ISO 7816 standard which enables such additional contact pads to be utilized for additional purposes such as to enable greater memory, communications, processing speeds and the like.
The present invention specifically addresses and alleviates the above-referenced deficiencies in the prior art. More particularly, the present invention contemplates the use of additional contact pads being formed on the smart card in the area located between the contact pads C1 through C4 and C5 through C8, which space heretofore has been used solely as a ground plane connected to contact pad C5. By increasing the number of contact pads, the additional pads can be used for numerous desired purposes such as input/output connections, memory and/or interfaces with specific functions, such as Serial Peripheral Interface (SPI).
To increase the number of contact pads, the present invention utilizes a flip chip package mounting technique for the integrated circuit processor which replaces the conventional prior art wire bonding die mounting technique. In the present invention, the integrated circuit flip chip is formed with an array of solder bumps or solder balls on one side thereof. The flip chip is mounted on a printed circuit board with the solder bumps connected to a printed circuit formed on the printed circuit board. Through vias formed in the printed circuit board, the flip chip pads and solder bumps are electrically connected to the contact pads formed on the opposing surface of the printed circuit board. Since the electrical connections between the flip chip and the contact pads is facilitated by the traces of the printed circuit board, which can be located beneath the flip chip (as opposed to only on the periphery thereof), the central area of the printed circuit is now free to include additional contact pads thereon. As a result, in addition to the contact pads standardized by ISO 7816, additional contact pads are provided which facilitate additional functions and/or interfaces to the smart card integrated circuit.
Preferably, the smart card connectors or pads provided by the present invention comprise the eight ISO 7816 standardized contact pads C1 through C8 and an additional five contact pads designated C9 to C13 which are available for more connections as desired. However, those skilled in the art will recognize that the number of additional contact pads may be varied as desired.
By use of the additional contact pads formed in the present invention, the integrated circuit and the functionality of the smart card can be significantly enhanced, for instance, incorporating differing communication ports, such as USB, SPI and SMB (System Management Bus) ports that communicates with devices in the reader such as serial memory and a real-time clock.
In one embodiment of the present invention, to communicate with the smart card, a conventional card reader can be modified with more connectors corresponding to the additional contact pads on the smart card that communicate with circuitry on the reader. Alternatively, two additional contact modules can be embedded in one smart card. Interconnects are formed to establish a mutual communication between these two die modules via circuitry in the reader.